In many off-highway operations, a machine operator must remain seated for extended periods of time while controlling operation of the machine. Seats may be designed to permit the operator to perform tasks from a comfortable position and isolate the operator, as much as possible, from vibrations of the machine. These vibrations may interfere with operator control and may cause the operator to fatigue more quickly.
A variety of seat suspensions have been designed to absorb and/or dissipate the forces imparted to the seat, including passive, semi-active, and active suspension systems. Passive suspension systems typically include a mechanical or air suspension coupled with a damper to dissipate the vibratory energy, and are popular because of their simplicity and cost compared to semi-active and active suspension systems. For example, U.S. Pat. No. 5,735,509 teaches a common scissors linkage system coupled with an air spring for vibration absorption and height adjustment.
The scissors type systems, however, including both the linkage and roller type scissors, have notable disadvantages. For example, the several pivot joints in the scissors linkage systems are all subject to wear and fatigue, and often result in the loosening of the mechanism. Roller type scissors systems are also subject to wear and failure, especially in response to lateral forces imparted to the scissors structure. Additionally, the scissoring action itself poses a risk to cut or twist hydraulic or pneumatic lines when the scissors mechanism is retracted quickly from an extended position. Therefore, there is a continuing need for suspensions that are simply constructed and inexpensive, while still providing the necessary absorption of vibrations over an expected machine life span.
The present disclosure is directed to one or more of the problems set forth above.